The present invention relates generally to techniques for reducing power consumption in a motor driven system, and more specifically to circuitry for generating a system wake up signal as a function of manual motor actuation in a motor driven system having a power conserving sleep function.
Passenger vehicles are typically equipped with a rear vehicle compartment for storing a spare tire and/or for transporting items such as groceries, luggage, tools, and the like. Some such vehicles, commonly known as sport utility vehicles, include a hatch or lift gate for accessing such a compartment. Passenger vans, on the other hand, typically include one or more sliding doors for accessing a rear passenger and/or storage compartment.
In vehicles of the foregoing type, control systems are known and currently available for automatically opening and/or closing lift gates and sliding doors. So-called xe2x80x9cpower lift gatexe2x80x9d and xe2x80x9cpower sliding doorxe2x80x9d systems may be physically or remotely actuated whereby a dedicated control circuit is operable to control one or electrically driven motors to drive the lift gate or door to either an open or closed position. Referring to FIG. 1, an example of one known motor control system 10 of the foregoing type is shown. System 10 includes a control circuit 12, such as a known microprocessor-based control unit, electrically connected to a motor actuation circuit 14 via a number, N, of signal paths 16, wherein N may be any positive integer. The motor actuation circuit 14 is of known construction and is electrically connected to an electrical motor 18 via a number, M, of signal paths 20, wherein M may be any positive integer. Motor 18 is typically a direct drive motor and includes a motor drive shaft L that is connected to an automotive door or lift gate 22 either directly or via mechanical linkage. A motor position determining circuit 24 of known construction is typically electrically connected to motor 18, or alternatively to motor actuator circuit 14, via a number, J, of signal paths 26, wherein J may be any positive integer. The motor position detection circuit is electrically connected to control circuit 12 via a number, K, of signal paths 28, wherein K may be any integer.
In operation, control circuit is operable to produce one or more motor control signals on signal paths 16, wherein motor actuation circuit 14 is responsive to the one or more motor control signals to produce one or more motor drive signals on signal paths 20. The motor 18 is, in turn, responsive to the one or more motor drive signals to correspondingly rotate its drive shaft L and thereby automatically drive movement of the door or lift gate 22. The control circuit 12 is typically operable to track the position of the door or lift gate 22 via one or more signals produced by the motor position circuit 24.
Currently, known power lift gate and power sliding door systems of the foregoing type operate in a stand-by mode of operation wherein electrical power is constantly applied to the system. This arrangement ensures that such systems are readily operable and that the control circuit may therefore instantaneously control the present gate/door position. However, such systems have a drawback in that electrical power is needlessly consumed thereby. It would accordingly be advantageous in such systems to provide for xe2x80x9csleepxe2x80x9d and xe2x80x9cwake-upxe2x80x9d modes of operation, wherein the system enters a low power consumption sleep mode after expiration of some predefined time period following gate/door actuation, and wherein the system wakes up to a full power operational mode upon manual gate/door actuation. Presently, however, no such systems are known that include the ability to wake up from sleep mode in response to manual gate/door actuation.
What is therefore needed is an improved power door/lift gate system operable in sleep and wake-up operational modes, wherein such a system includes a reliable mechanism for waking up from sleep mode operation in response to manual door/lift gate movement.
The foregoing shortcomings of the prior art are addressed by the present invention. In accordance with one aspect of the present invention, circuitry for producing a wakeup signal based on back electromotive force (EMF) of a motor comprises a motor having a drive shaft and at least one input for receiving a motor drive signal, wherein the motor is responsive to the motor drive signal to rotate the drive shaft, wherein the motor produces a back EMF signal at the at least one input in the absence of the motor drive signal and in response to rotational movement of the drive shaft, and a wakeup circuit having an input connected to the at least one input of the motor and an output, wherein the wakeup circuit is responsive to the back EMF signal at the input thereof to produce a wakeup signal at the output thereof.
In accordance with another aspect of the present invention, a method for producing a wakeup signal in a motor control system based on back electromotive force (EMF) of an electrically driven motor comprises the steps of monitoring an electrical input of a motor having a drive shaft, wherein the motor is responsive to a motor drive signal to rotate the drive shaft, and wherein the motor produces a back EMF signal in response to movement of the drive shaft in the absence of the motor drive signal, and producing a wakeup signal is response to detection of the back EMF signal.
One object of the present invention is to provide an electrical circuit for producing a wakeup signal as a function of back electromotive force (EMF) of a motor.
Another object of the present invention is to utilize such a circuit in an electrical motor control system operable to drive a power sliding door or power lift gate assembly in an automotive environment.
Another object of the present invention is to utilize such a circuit in such an electrical motor control system that is operable in a reduced-function, reduced-power consumption sleep mode of operation and in a full-function, full-power consumption wakeup mode of operation, for waking up the system from sleep mode in response to manual actuation of the door or lift gate.
These and other objects of the present invention will become more apparent from the following description of the preferred embodiments.